The present invention relates to a method for generating a multi-dimensional image of a sample. The present invention also relates to a system for generating the multi-dimensional image of a sample.
Three-dimensional data acquisition and volume visualization through the application of serial FIB (Focused Ion Beam) sectioning has recently emerged as a potential method to acquire, interrogate, and display multi-dimensional images for various substrate materials. For example, in U.S. Pat. Nos. 6,855,936 and 7,750,293 B2, certain systems are described which can be used for FIB-SEM (Scanning Electron Microscope) three dimensional imaging methods. The FIB system can act like a nanoscale scalpel to remove very thin slices of material from a sample, while the SEM captures images of the sample's structure at each slice. Factors which may limit wider utilization of FIB-SEM based three dimensional imaging methods include challenges in implementing rapid and accurate image data analysis and image volume generation methods for the images captured with these devices.
In the field of digital rock physics, devices for generating computer tomographic (CT) images of rock samples, such as drill cuttings, have become available and used to analyze the rock samples. Such CT image generating devices have been used to produce two-dimensional gray scale images of the rock samples. The two-dimensional images can be stacked into a three-dimensional volume. Such gray scale images have been used, for example, as part of an analysis to obtain estimates of petrophysical parameters of the imaged rock sample, for example, porosity, permeability, shear and bulk moduli, and formation resistivity factor.
The present investigators have recognized that it would be beneficial to generate ultra-high resolution multi-dimensional images of rocks or other materials in combination with powerful automated analytical capabilities for image alignment and corrections to enable accurate and consistent nanoscale analysis of hydrocarbon deposits in rock or other samples. This development could permit rapid and accurate understandings of a rock sample, such as in terms of the geological phase content and distribution for any individual two-dimensional slices and the three-dimensional volume as a whole without need of laboratory analysis of the sample and with reduced reliance or need of human or manual analysis as part of the methodology. The present investigators further have recognized that there is a need for unique digital image capture and analysis methods which can provide accurate understandings in a short period of time for unconventional or “tight” fine grained formation rocks. Tight formations can have extremely low permeability unlike more typical sandstones or other more porous rocks which have been analyzed using digital rock physics.